Music composition and generation has been largely an artistic endeavor involving composers, musicians, recording engineers and the like to create melodies for pleasure or commercial use. Computer-generated music has been pursued in recent years for two reasons: academic curiosity and commercial demand for inexpensive, textural music for a variety of media applications including film, video, web sites, games and wireless applications. It is the latter reason that has economic implications, for a number of companies and consumers are looking for textural or ambient music that is inexpensive, easy to produce, as rights-free as possible and that follows essential psychoacoustic principles in composition. Computer music generation systems typically use MIDI (Musical Instrument Digital Interface) to control the electronic musical instruments.
Computer-generated music in real time has used a variety of systems or methodologies in an attempt to achieve these goals. Current systems, such as Sseyo's Koan system or the method as described in U.S. Patent Application Publication No. 20010025561 to Milburn use stochastic methods or metrics. Using the stochastic method, music is generated using random numbers to determine a variety of musical parameters within user specified constraints. The Koan system is an embodiment of this approach. The issues with the stochastic method are that the music may not be complex enough to adhere to the psychoacoustic principles that make the music sound as if it was composed and played by humans. In addition, this system can be difficult to use for those not conversant in music.
Milburn's approach to automatic music generation relies on pre-specified musical phrases, which are then analyzed using a metrics technique which allows the composer to morph between two different phrases. This technique requires a higher level of specification than the Cellular Automata Music Generator (CAMG) system described herein, in that the musical phrases must be pre-composed.
Another system used in music generation is the mathematical model cellular automata (CA). CA methodology lends itself to music generation because of the nature of this mathematical model. The CA theory stems from the notion that simple systems can generate complex behavior or patterns. This makes it ideal for music generation that requires complex output using simple and lightweight systems. In addition, CA systems are easy to modify on a global basis. Under a CA model, one parameter change can result in global dynamic behavior that is either predictable, complex, periodic or random. The system is also deterministic; therefore given the same parameters, the same musical piece will be generated and evolve in the same way each time, giving the user an element of necessary control.
There has also been work in music generation using CA, but it has been either using 2-dimensional models or applying simple 1-dimensional CA to a specific musical content, such as rhythm, to create simply a general beat or a series of notes. The issues with 2-dimensional models is that the systems are complex to use and have memory and processing requirements that are too high for average personal computer, wireless device or console systems. A number of authors have published related techniques to CAMG on the Internet (for example, Reiners, Millen, and Miranda). Reiner's system, named Automatous Monk, relies upon elementary 1D CA to generate musical parameters, however his currently published work is far more primitive in its application. For example, 1D CA are only used to generate pitch values for the composition, resulting in a far less complex final output.
Miranda's CAMUS is a generative music system in that it is based upon CA technology, but relies on complex 2D CA implementations. Milburn's approach to generative music employs a technique which creates a metric between two pre-composed musical phrases and allows the user to morph between them.
Sseyo's Koan uses purely random or stochastic techniques with constraints provided by the composer in areas such as which scale to use, and the range of note choices. Koan has a steep learning curve and requires the user to have musical knowledge. Koan is concentrated on the mobile and web site market.
Leach (U.S. Patent Application Publication No. 20030183065) employs a strictly rule based networking approach that does not use any CA based techniques
Georges (U.S. Patent Application Publication No. 20030131715) employs a rule-based approach that does rely on stochastic variables. This approach is more closely related to Koan.